User Manual

Chapter 1

BOSCH HDI EDC 15C2 INJECTION SYSTEM AND PARTICLE FILTER

B - MAIN DESIGN OF THE DW12 TED4 ENGINE

Up until now, diesel engines fitted to touring cars have used indirect injection.

In indirect injection, the fuel is injected under a maximum pressure of 300 bar into

a combustion prechamber.

In direct injection, the fuel is injected directly onto the top of the piston.

Engine efficiency is improved due to:

• better quality of the air/fuel mixture,

• reduction in heat losses,

• direct combustion in the cylinders.

Features of the new cylinder head design of the DW12 TED4 engine:

• cylinder head with 16 valves,

• specific location of the diesel injectors (central and vertical, optimisation of

air/fuel mixture),

• double complex shape air inlet manifolds in the cylinder head (variable swirl),

• no precombustion chamber,

• specific location of the heater plugs (on the rear of the cylinder head).

Modifications used to improve the efficiency of the DW12 TED4 engines:

• variable geometry turbocharger (higher turbocharging pressure at low engine

speeds),

• optimisation of the inlet and exhaust manifolds,

• roller valve rockers limiting losses caused by friction,

• weight reduction.

Note: The above modifications also help to reduce pollutant emissions

directly.

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